Why eating sugar impairs your ability to conceive.

By February 14, 2012Sugar

Female infertility is increasing at an astounding rate in Australia.  The rate of increase of Type II diabetes is strapped to the same rocket.  Now a series of new studies suggest the cause for both is the humble fructose molecule found in every teaspoon of sugar added to your food by your local processed food conglomerate.

As many as one in five Australian women of reproductive age now have PolyCystic Ovary Syndrome (PCOS). Exact data on the numbers affected are hard to come by because up to 70 percent of PCOS cases have not been medically diagnosed.

The symptoms usually include acne, the appearance of male patterns of hair growth (and male baldness) and irregular or absent periods.  Ok so it’s not pleasant, but the big impact is on fertility.  PCOS is the primary cause of female infertility in Australia today.  The reason that doctors suspect that the syndrome goes largely undiagnosed is that pretty much the only time it’s tested for is when a woman seeks fertility treatment.

A recent Swedish evaluation concluded that women with PCOS were 9 times as likely to need access to IVF as women without the syndrome.  IVF is the last resort in fertility treatment.  It is used when everything else has failed.  And it is being used increasingly frequently.  In Australia today approximately one in every 30 children is born as a result of IVF.

IVF is not a path women choose lightly.  It’s an experience that comes bundled with significant psychological and emotional costs.  And at a monetary cost of approximately $32,000 per birth it’s an increasingly expensive burden on mothers, families and the public health system as well.  The number of IVF treatments grew by 50% between 2004 and 2009 and is currently increasing by about 14% every year.

As you might expect from a glance at the symptoms, PCOS is a result of there being too much testosterone (the male sex hormone) in circulation.  Testosterone is not an exclusively male hormone.  Women have it too, but generally circulating at about 10 percent of the male level.

Doctors have long known that women with PCOS not only have higher circulating testosterone, but they also have extremely low levels of very important protein, the charmingly named Sex Hormone-Binding Globulin (SHBG).

One of SHBG’s jobs is to keep testosterone out of circulation.  By binding to testosterone, SHBG controls the amount of free (and therefore active) testosterone in our bloodstream.  Having low levels of SHBG seems to result in there being too much free testosterone in women.

It’s also well established that people who are obese or who have insulin resistance or Type II Diabetes have extremely low levels of SHBG.  In fact low SHBG is such a reliable indicator of insulin resistance that SHBG testing is being proposed as a good early indicator of the development of Type II Diabetes.

Hormones are complex things (and that’s an understatement) and sex hormones are the big daddy of complexity.  Because they are constantly produced and their actions depend on the presence or absence of other sex hormones and what sex you are, it’s very hard to tease out the cause and the effect.

For a long time researchers have believed that insulin resistance is the cause of the low levels of SHBG.  That would mean that PCOS is a consequence of being insulin resistant but a January 2012 study has shown that is not the case.  It turns out that insulin levels do not affect the level of SHBG, but the presence of fat around the liver affects both the insulin level and the SHBG level.

One really sure way to create a fatty liver is to consume large amounts of fructose.  Because fructose is (directly and immediately) converted to fat (by our liver) it’s the single most efficient way to get the job done.

The best way to prove that theory is of course to try feeding a healthy person high quantities of fructose and see if they develop fatty liver, insulin resistance and PCOS.  Because volunteers for that kind of fun might be a bit thin on the ground researchers have had to resort to rats as the model.

You can’t use any old garden variety rats.  To be certain you need to use rats that have been bred with the human gene for the production of SHBG.  Before you get out the rat breeding equipment (whatever that might be) you might like to know it’s already been done.

In 2007 a group of Canadian researchers tried feeding so-called transgenic rats glucose and fructose to see what happened.  They found both sugars suppressed SHBG production but fructose was twice as effective (glucose 40%, fructose 80% suppression) and fructose was especially quick, causing its damage after just three days.  They found the SHBG effect was caused by the accumulation of the fats created as a result of processing the fructose.

Joining some dots here it does not seem like a big leap to say that insulin resistance, Type II Diabetes, fatty liver disease and PCOS are all part of the same bunch of joy you can expect from consuming fructose.

Fructose directly increases the amount of circulating testosterone in women.  More testosterone directly impairs a woman’s ability to conceive.  The single most effective way for a woman to increase her chances of having a baby is for her to stop eating fructose.

When fructose is removed, hormone levels return to normal, PCOS symptoms disappear and fertility is restored.  It really is that simple.  There is no reason (other than financial) that the first words out of a fertility doctor’s mouth shouldn’t be “Stop eating sugar.”


Photo by Ⅿeagan. Distributed under the Creative Commons License.

Join the discussion 11 Comments

  • Thomas T says:

    Whilst I am all for your quest to help people improve their health, you really do need to stop relying on animal/rodent data…

    Newsflash: Rats are not humans…

  • LizzieBee says:

    Hi David,
    I caught the very end of your interview with Margaret Throsby on Tuesday (was in Tax Class, I aim to listen to the whole podcast on the weekend) and I just wanted to find you online & cheer on your “SUGAR = BAD” message.
    Sugar is just SO BAD for you! My partner & I discovered the “Slow Carb Diet” last year and have had good success in losing our weight. But the thing that we’ve taken out of the diet the MOST is how much SUGAR we consume on a daily basis. What foods convert STRAIGHT into sugar (ie, empty carbs) when consumed: things like wheat (therefore pasta & bread), rice, CORN (of all things) and how much sugar is in FRUIT. Dieticians tell us to eat 2 pieces of fruit each day, but that is a LOT of fructose your body is consuming.
    The thing we look at MOST on the nutritional labels on food now is “Is sugar included in the ingredients?” and “how much sugar is IN the product?” Sugar can occur naturally in foods, like fruit, but it doesn’t mean that it’s OK to be eat in any sort of quantity.
    Good for you!

  • Deb says:

    is that true, David, that ’empty carbs’ are converted into sugar? This is not what I understand from reading your books. Only sucrose is converted into fructose, right?

  • Marie says:

    Deb, carbs are converted into glucose (the other half of table sugar). Your body needs glucose but excess glucose isn’t good for anyone. It’s definitely not as bad as fructose though.

  • Deb says:

    Thanks, Marie, yes, I knew that, carbs to glucose. Even ’empty carbs’ like white bread etc. So they are not converted to ‘sugar’. And glucose = ‘good’, unless as you say there is too much of it. So that is why I was querying the previous post. I have been off sugar for about 6 weeks now, and am surprised how fast the weight is coming off seeing as I was not a big sugar eater.

  • Yep that’s right Deb – most things described as carbs are converted to glucose. It is only fructose itself or sucrose (sugar) which is a 50/50 combination of glucose and fructose which presents a problem from a fructose perspective.


  • Ms Eat4Life says:

    This comment has been removed by the author.

  • Ms Eat4Life says:

    Firstly, big thanks to David for taking the time in your life to uncover the truths about sugar and to share your knowledge with the world. I will be forever grateful.

    Thanks for a great article here too.

    I am probably the worst of all sugar addicts (well, I was).. 2 blocks of chocolate a day, (that’s the big family blocks) plus the standard sugary snacks in-between meals for at least 15 years. I know, shocking. I am 32 now and have been trying to conceive for the last 12 months with no luck. It was confirmed 3 months ago that I have PCOS. I have limited by sugar somewhat since then however still not the best.. (a litre of ice-cream a day). I started reading David’s book The Quit Plan a week ago and have been sugar free since. Since reading the Quit Plan I am actually disappointed (only now!) in myself for abusing my body like this for so long… I have a bmi of 22, always have, so the sugar rarely affected my weight a great deal. Now it’s evident that the damage was happening elsewhere in my body (PCOS + who knows yet?). I know the liver regenerates itself so I am confident that by living a sugar free life, I will fall pregnant… soon.

    P.s. With 7 kids on my mother’s side AND 9 kids on my father’s side, there is no history of pcos in the family…

    P.s.s And if you are wondering why I didn’t give up sugar on David’s first book, it’s because I haven’t read it yet.


  • Spoc_djbj says:

    David thank you for such an informative and interesting read.
    i was diagnosed with PCOS and insulin resistance when i was 16 yrs old. even though specialists can tell you to do something to correct this i was not really in the frame of mind to follow their direction. 8 years later and i still have these conditions but over recent months my mind set has changed and want to make a change for the better. your details on studies and information in this article as well as your book helps me keep focused on wanting to better myself. i really appreciated all your research you are doing and i look forward to reading more.

    thanks again

  • Pascale says:

    So, no fruit? Nature’s sweets? Hmmm…. dunno about that. If we ate what grew out of the ground and on a tree or bush more often that what comes out of a packet, I’m sure we’d all be better off, without the need to cut out any true food group at all.

  • Cadence says:

    I am conducting a survey regarding female infertility for part of an independent study project and I’ll be looking at the link between infertility and sugar intake. It will account for 15% of my final grade, so I definitely appreciate every person! It is targeted towards adult women who have been trying to conceive, but are yet to be successful. If you fit the criteria, please take the survey, but also share it with anyone you do know that is struggling with this issue and maybe just help me get this out there. Thank you!
    Here is a link to the survey:

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